This application claims the priority of German patent document 199 08 907.8, filed Mar. 2, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process and apparatus for automatic adjustment of the handling of a motor vehicle having an internal-combustion engine.
German Patent Document DE 35 23 352 C2 discloses a process for automatically controlling the driving speed of a motor vehicle, in which the actual vehicle speed is sensed and, in the event of a deviation from a desired value, both automatic acceleration control and automatic speed control are started, taking into account the relationship for the throttle valve angle as a function of the desired speed and the actual speed. In its basic structure, this process corresponds to a conventional automatic speed control, in which an automatic control unit generates adjusting signals from measuring signals according to a defined calculating rule, for adjusting diverse vehicle components.
The journal article from Elektronik 18/1995, Pages 44 to 46, Vol. 48, with the title xe2x80x9cSmoothly Acceleratedxe2x80x9d by Wolfgang Rode and Raimund Schuetz describes a method for controlling an electric drive motor of a motor scooter, using a fuzzy logic. To avoid dangerous driving situations, a number of conditions are formulated; that is, operating and condition quantities reflected in logic variables are linked with one another and are examined with respect to their truth content according to a fixed testing logic. The vehicle speed, the position of the throttle twist grip, the battery voltage and the current intensity are determined as the operating and condition quantities, and are divided into defined categories corresponding to their value.
By means of logical conditions to be tested cyclically, a number of dangerous situations, such as the rearing-up of the vehicle as the result of a very high starting torque, are prevented.
However, this method is limited to the use of electric motors. It cannot be used to control (automatically or otherwise) components in vehicles having an internal-combustion engine.
One object of the invention is to provide a method and apparatus for detecting driving situations in motor vehicles having an internal-combustion engine, and for controlling vehicle handling as a function of the determined driving situation.
This and other objects and advantages are achieved by the method and apparatus according to the invention for automatically adjusting the handling of a motor vehicle operated by an internal-combustion engine, in which a set or rules is used to detect the start and the ending of three different driving conditions: constant drive, acceleration and deceleration. For this purpose, certain vehicle operating parameter values and vehicle operating mode (condition) values are detected or determined, advantageously in successive, hierarchically arranged steps, and are linked in an automatic control unit by means of the defined set of rules. Upon occurrence of the start or the end of one of such driving conditions the automatic control unit generates adjusting signals, which are supplied to, and used for automatic adjustment of, the corresponding vehicle or motor components.
In this manner, it is possible to take corresponding measures at the start and end of a driving situation, to achieve improved economy and/or a safety relevant driving strategy. For example, after the start of a deceleration is triggered by the actuation of the foot brake, it is possible to prepare, initiate or carry out additional braking measures (such as activating the engine brake) to assist the braking operation.
The conditions recorded in the set of rules for determining the start and end of constant driving, acceleration and deceleration are formulated in different manners. This can be accomplished by defining different rules for the start and for the end of one driving condition respectively; in particular, this can be done by defining different reference values for one and the same operating or condition value which is used as the basis for assessing the start and end of an actual driving condition. In this manner, a type of hysteresis function can be implemented to determine the start and end of a driving condition. This arrangement positively influences the decision for the start and end to such an extent that inaccuracies or rapid shifting back and forth between two shifting conditions can be avoided. Expediently, higher reference values are defined for the start of a vehicle condition than for its end, so that undesirably fast shifting between two driving conditions is avoided. As the result a smoothing of the functions is achieved for acceleration, constant driving and deceleration.
As the operating and conditions values, first one or several of the values, xe2x80x9cclutch closedxe2x80x9d (clutch status), xe2x80x9cvehicle stopsxe2x80x9d (vehicle driving status), xe2x80x9cvehicle brake is usedxe2x80x9d (brake status) and xe2x80x9cretarder is usedxe2x80x9d (retarder status), are determined (either directly by measuring or indirectly by processing measured values). These values are determined, expediently in a preceding step (data preprocessing), before the linking of the operating and condition quantities is carried out according to defined rules.
One or more of the values, vehicle acceleration, vehicle speed, accelerator pedal position, accelerator pedal velocity, road inclination, change of the road inclination and torque difference, as well as the change of the difference between the torque desired by the driver and the actual drive torque, are determined as additional values for assessing the vehicle condition.
The measured or calculated operating and condition quantities are processed individually or combined in a set of rules stored in the control unit, and are used to determine whether the vehicle is currently at the start or end of an acceleration operation, a deceleration operation or a constant drive.
Both logical values (states) and numerical values can be used as operating and condition quantities. The values determined in data preprocessing advantageously are logical values (states); the remaining operating and condition quantities are numerical values. A combined query of the logical and the numerical values takes place in the set of rules.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.